Diclofenac, [(2,6-dichloro-anilino)-2-phenyl]-2-acetic acid, is a nonsteroidal anti-inflammatory drug (NSAID) with the following structure:

Diclofenac also has analgesic and antipyretic properties. Diclofenac works by blocking cyclooxygenase. The blocked cyclooxygenase fails to trigger production of prostaglandins, which are responsible for creating pain, swelling and inflammation in response to injury and certain conditions.
Diclofenac is commercially available as a tablet from Novartis (e.g., Cataflam®; Cataflam is a registered trademark of Novartis Corporation). The Orange Book (The Food and Drug Administration's publication listing drug products approved under section 505 of the Federal Food, Drug, and Cosmetic Act) indicates that diclofenac has also been formulated as a capsule, patch, and gel. Diclofenac has also been administered via injection and rectal suppositories.
Diclofenac has been administered for the treatment of many conditions and disorders including migraines, rheumatoid arthritis, osteoarthritis, actinic keratosis, ankylosing spondylitis, bursitis, tendonitis, soft tissue disorders such as sprains and strains, renal colic, acute gout, dysmenorrhea, and pain following surgery.
U.S. Pat. No. 7,759,394 is directed to methods of treating migraines associated with phonophobia and photophobia that involve administration and ingestion of a liquid 50 milligrams diclofenac formulation in combination with an alkali metal carbonate or bicarbonate. One problem with ingestion of such a formulation is that diclofenac is subject to the hepatic first pass metabolic process that decreases bioavailability. Another disadvantage of such a formulation is that some patients have difficulty swallowing (dysphagia). In addition, drugs that are ingested (e.g. tablets, capsules, solutions) must be absorbed into the blood stream through the stomach or intestine which causes a delay in action.
Patches and gels containing diclofenac may lead to dryness, redness, itching, swelling, irritation, or numbness at the application site(s). Patches and gels are also limited to the treatment of pain or swelling in proximity to the transdermal application site.
Diclofenac has been proven to provide relief from many conditions. While some diclofenac formulations are available to patients in need of diclofenac treatment, there is still a need for new diclofenac formulations with quicker on-set, higher bioavailability, and improved storage stability.